Dry electrode manufacture with lubricated active material mixture

ABSTRACT

A method of manufacturing a free-standing electrode film includes preparing a mixture including an electrode active material, a binder, and an additive solution or conductive paste, the additive solution or conductive paste being in an amount less than 5% by weight of the mixture and including a polymer additive and a liquid carrier, as well as a conductive material in the case of a conductive paste. The mixture may have total solid contents greater than 95% by weight. Preparing the mixture may include mixing the additive solution or conductive paste with the electrode active material to lubricate the electrode active material and subsequently adding and mixing in the binder. The method may further include subjecting the mixture to a shear force and, after the mixture has been subjected to the shear force, pressing the mixture into a free-standing film.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND 1. Technical Field

The present disclosure relates generally to manufacturing electrodes forenergy storage devices such as batteries and Li-ion capacitors and, moreparticularly, to the manufacture of a free-standing electrode film by adry process.

2. Related Art

As demand for inexpensive energy storage devices increases, variousmethods have been proposed for manufacturing electrodes. Among these,there exist so-called “dry” processes by which a free-standing electrodefilm may be manufactured while avoiding the expense and drying timeassociated with the solvents and aqueous solutions that are typicallyused in slurry coating and extrusion processes. In order to producehigher quality electrodes by such a dry process that may result inenergy storage devices having higher energy density, the amount ofbinder mixed with the active material should be minimized within a rangethat still allows for an electrode film to be reliably produced withoutexcessive breakage. To this end, the binder may be chemically activatedto improve its adhesion strength by the addition of a highly vaporizablesolvent as described in the present inventor's own U.S. Pat. No.10,069,131, entitled “Electrode for Energy Storage Devices and Method ofMaking Same,” the entirety of the disclosure of which is whollyincorporated by reference herein. However, further reduction in theamount of binder needed is desirable, especially in the case ofproducing electrodes for batteries, whose active materials may requiremore binder than those of ultracapacitors and other energy storagedevices.

One method for further reducing the amount of binder needed is bytemperature activation of the binder, either alone or in combinationwith chemical activation, as described in the present inventor's ownU.S. patent application Ser. No. 16/874,502, filed May 14, 2020 andentitled “Dry Electrode Manufacture by Temperature Activation Method,”the entirety of the disclosure of which is wholly incorporated byreference herein. Active material loading and the electrode film qualityimproves significantly by a combination of chemical activation and/ortemperature activation when making battery electrodes using the drymethod.

Despite the above improvements, higher active loading formulations andbetter electrode quality remains desirable.

BRIEF SUMMARY

The present disclosure contemplates various methods for overcoming thedrawbacks accompanying the related art. One aspect of the embodiments ofthe present disclosure is a method of manufacturing a free-standingelectrode film. The method may comprise preparing a mixture including anelectrode active material, a binder, and an additive solution, theadditive solution being in an amount less than 5% by weight of themixture and including a polymer additive and a liquid carrier, themixture having total solid contents greater than 95% by weight. Thepreparing of the mixture may comprise mixing the additive solution withthe electrode active material to lubricate the electrode active materialand subsequently adding and mixing in the binder. The method may furthercomprise subjecting the mixture to a shear force and, after the mixturehas been subjected to the shear force, pressing the mixture into afree-standing film.

The method may comprise mixing the polymer additive with the liquidcarrier to produce the additive solution.

The polymer additive may be 0.5-10% by weight of the additive solution.The polymer additive may be 1-5% by weight of the additive solution.

The mixture may include a conductive material. The preparing of themixture may comprise mixing the additive solution with the electrodeactive material to lubricate the electrode active material andsubsequently adding and mixing in the binder and the conductivematerial.

The pressing of the mixture into a free-standing film may includeapplying a roller press to the mixture.

Another aspect of the embodiments of the present disclosure is a methodof manufacturing a free-standing electrode film. The method may comprisepreparing a mixture including an electrode active material, a binder,and a conductive paste, the conductive paste being in an amount lessthan 5% by weight of the mixture and including a polymer additive, aliquid carrier, and a conductive material, the mixture having totalsolid contents greater than 95% by weight. The preparing of the mixturemay comprise mixing the conductive paste with the electrode activematerial to lubricate the electrode active material and subsequentlyadding and mixing in the binder. The method may further comprisesubjecting the mixture to a shear force and, after the mixture has beensubjected to the shear force, pressing the mixture into a free-standingfilm.

The method may comprise mixing the polymer additive, the liquid carrier,and the conductive material to produce the conductive paste. The mixingof the polymer additive, the liquid carrier, and the conductive materialto produce the conductive paste may comprise mixing the polymer additiveand the liquid carrier to produce an additive solution and, thereafter,mixing the conductive material into the additive solution. The polymeradditive may be 0.5-10% by weight of the additive solution. The polymeradditive may be 1-5% by weight of the additive solution.

The conductive material may be 1-20% by weight of the conductive paste.The conductive material may be 2-15% by weight of the conductive paste.The conductive material may be 5-10% by weight of the conductive paste.

The mixture may include a second conductive material other than theconductive material included in the conductive paste. The preparing ofthe mixture may comprise mixing the conductive paste with the electrodeactive material to lubricate the electrode active material andsubsequently adding and mixing in the binder and the second conductivematerial.

The pressing of the mixture into a free-standing film may includeapplying a roller press to the mixture.

Another aspect of the embodiments of the present disclosure is a methodof manufacturing an electrode. The method may comprise performing eitherof the above methods and laminating the resulting free-standing film ona current collector.

Another aspect of the embodiments of the present disclosure is a powderymixture for use in manufacturing a free-standing electrode film. Thepowdery mixture may comprise an electrode active material, a binder, andan additive solution in an amount less than 5% by weight of the powderymixture, the additive solution including a polymer additive and a liquidcarrier. The powdery mixture may have total solid contents greater than95% by weight.

The powdery mixture may further comprise a conductive material.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the various embodimentsdisclosed herein will be better understood with respect to the followingdescription and drawings, in which like numbers refer to like partsthroughout, and in which:

FIG. 1 shows an example operational flow for manufacturing afree-standing electrode film or an electrode produced therefrom;

FIG. 2 shows an example sub-process of step 110 in FIG. 1 ; and

FIG. 3 shows another example sub-process of step 110 in FIG. 1 .

DETAILED DESCRIPTION

The present disclosure encompasses various embodiments of methods andmixtures for manufacturing a free-standing electrode film or anelectrode produced therefrom, as well as the resulting films,electrodes, and energy storage devices. The detailed description setforth below in connection with the appended drawings is intended as adescription of several currently contemplated embodiments and is notintended to represent the only form in which the disclosed invention maybe developed or utilized. The description sets forth the functions andfeatures in connection with the illustrated embodiments. It is to beunderstood, however, that the same or equivalent functions may beaccomplished by different embodiments that are also intended to beencompassed within the scope of the present disclosure. It is furtherunderstood that the use of relational terms such as first and second andthe like are used solely to distinguish one from another entity withoutnecessarily requiring or implying any actual such relationship or orderbetween such entities.

FIG. 1 shows an operational flow for manufacturing a free-standingelectrode film or an electrode produced therefrom. Unlike conventionaldry processes, the process exemplified by FIG. 1 includes thelubrication of the active material mixture that will be pressed into afree-standing film. This may be achieved by mixing a polymer-containingadditive solution or conductive paste with the electrode active materialprior to adding a binder, as shown by way of example in the operationalflows of FIGS. 2 and 3 (which represent sub-processes of step 110 inFIG. 1 ). The resulting powdery mixture may be pressed into afree-standing electrode film of superior quality, allowing for lowerbinder content and higher active loading formulations. As a result, thedisclosed processes can produce an energy storage device with improveddischarge characteristics including higher discharge capacity, higherfirst cycle efficiency, and higher C rate.

The operational flow of FIG. 1 may begin with a step 110 of preparing alubricated electrode active material mixture. Referring by way ofexample to FIG. 2 , which shows an example sub-process of step 110, theactive material mixture may be lubricated by the addition of an additivesolution. First, in step 210, the additive solution may be produced bymixing a polymer additive with a liquid carrier. The polymer additivemay be a polymeric compound, surfactant or high viscosity liquid (e.g.mineral oil or wax) such as those known to be used as a dispersant forcarbon nanotubes or as a binder. See, for example, U.S. Pat. No.8,540,902, which provides example dispersants and polymeric bindersincluding polyethylene, polypropylene, polyamide, polyurethane,polyvinyl chloride, polyvinylidene fluoride, thermoplastic polyesterresin, polyvinylpyrrolidone, polystyrene sulfonate, polyphenylacetylene,polymeta-phenylenevinylene, polypyrrole, polyp-phenylenebenzobisoxazole, natural polymers, amphiphilic materials in aqueoussolutions, anionic aliphatic surfactant, sodium dodecyl sulfate, cycliclipopeptido bio surfactant, water-soluble polymers, polyvinyl alcoholsodium dodecyl sulfate, polyoxyethylene surfactant, polyvinylidenefluoride (PVDF), carboxyl methyl cellulose (CMC), hydroxyl ethylcellulose polyacrylic acid, polyvinyl chloride and combinations thereof.Another example polymer additive may be styrene-butadiene rubber (SBR).

The present disclosure contemplates the use of one or more of suchpolymers as an additive to lubricate the electrode active material.Thus, whereas these compounds may conventionally be added to a wetmixture (e.g. a solution containing a large quantity of a solvent suchas n-methylpyrrolidone) to function as a carbon nanotube dispersant or abinder when producing an electrode by a coating method as exemplified byU.S. Pat. No. 8,540,902, the processes of the present disclosureintroduce the polymer additive as a way of lubricating a predominantlydry or powdery mixture using only a small amount of a liquid carrier(e.g. less than 5% by weight of the mixture). The lubricating effect ofthe polymer additive is found to improve the quality of the resultingfree-standing film in the disclosed dry electrode manufacturing process,making it possible to use less binder and thus more active material.

The liquid carrier used to produce the additive solution may be aqueousor non-aqueous and may, for example, include one or more chemicalsselected from the group consisting of n-methylpyrrolidone, ahydrocarbon, an acetate ester, an alcohol, a glycol, ethanol, methanol,isopropanol, acetone, diethyl carbonate, and dimethyl carbonate. Theliquid carrier may be chosen for its ability to dissolve the polymeradditive and for its vaporization temperature, which may be at or higherthan 70° C., for example. The polymer additive may be mixed with theliquid carrier using any type of mixing tool, such as a hand mixer, ablender, or an industrial mixer, until the polymer additive is dissolvedin the liquid. The polymer additive may be 0.5-10% by weight of theadditive solution, preferably 1-5% by weight of the additive solution.As one example, the liquid solution may consist of 1.33% (by weight)polyvinylpyrrolidone as the polymer additive and 98.67%n-methylpyrrolidone as the liquid carrier.

The operational flow of FIG. 2 may continue with a step 220 of mixingthe additive solution (including the polymer additive and the liquidcarrier) with an electrode active material to lubricate the activematerial surface. In the case of manufacturing an electrode for use in alithium ion battery, the electrode active material may be, for example,lithium manganese oxide (LMO) in an amount 82-99% (e.g. 94%) by weightof the final mixture that is eventually pressed into a free-standingfilm (which may further include a binder and/or conductive material asdescribed below). Other examples of active materials that may be usedwith the disclosed processes include manganese dioxide or other metaloxides, intercalated carbon, hard carbon, or activated carbon, dependingon whether the electrode to be manufactured will be used in a battery,ultracapacitor, lithium ion capacitor, fuel cell, or hybrid cell, forexample. The additive solution may be mixed with the electrode activematerial using any type of mixing tool, such as a hand mixer, a blender,a kitchen mixer, an industrial mixer, or a mill until the activematerial is lubricated by the additive solution uniformly. As notedabove, the addition of the additive solution to the active material mayadd only a small amount of liquid, such that the resulting mixtureremains powdery. Quantitatively, the additive solution may be less than5% by weight of the final mixture, and the final mixture may have totalsolid contents greater than 95% by weight.

Once the electrode active material has been lubricated by the additivesolution, a binder may be added and mixed in (step 230). The binder maybe, for example, polytetrafluoroethylene (PTFE) or another thermoplasticpolymer and may be in an amount 1-8% by weight of the final mixture,preferably less than 3% in the case of manufacturing an LMO electrodefilm for a battery. In some cases, the amount of binder needed may befurther reduced by chemically activating the binder using a solvent asdescribed in U.S. Pat. No. 10,069,131, which may cause the binder tosoften further and become more able to stretch without breaking. Theselected solvent for activating the binder may have a relatively lowboiling point of less than 130° C. or less than 100° C. (i.e. less thanthe boiling point of water) and may, for example, include one or morechemicals selected from the group consisting of a hydrocarbon, anacetate ester, an alcohol, a glycol, ethanol, methanol, isopropanol,acetone, diethyl carbonate, and dimethyl carbonate.

Before or after the addition of the binder, a conductive material mayalso be added and mixed in (step 240), depending on the conductivity ofthe active material. The conductive material may be, for example,activated carbon in an amount 0-10% (e.g. 4%) by weight of the finalmixture. Other example conductive materials are a conductive carbonblack such as acetylene black, Ketjen black, or super P (e.g. a carbonblack sold under the trade name SUPER P® by Imerys Graphite & Carbon ofSwitzerland), carbon nanotubes (CNT), graphite particles, a conductingpolymer, and combinations thereof.

Referring back to FIG. 1 , the operational flow may continue with a step120 of subjecting the lubricated electrode active material mixture to ashear force. The mixture may, for example, be blended in a blender, suchas an ordinary kitchen blender or an industrial blender. Adequate shearforce to deform (e.g. elongate) the binder, resulting in a stickier,more pliable mixture, may be achieved by blending the mixture in such ablender at around 10,000 RPM for 1-10 min (e.g. 5 min). Preferably, ahigh-shear mixer may be used, such as a high-shear granulator (e.g. ajet mill). If the binder is to be chemically activated by a solvent asdescribed above, the solvent may in some cases be injected into themixture while the mixture is being subjected to the shear force in step120.

After the mixture has been subjected to the shear force, the operationalflow of FIG. 1 may continue with a step 130 of pressing the mixture toproduce a free-standing film, for example, using a roller press (e.g. ata temperature of 150° C. and a roll gap of 20 μm). Owing to thelubrication of the active material mixture in step 110, the resultingfilm may be of high structural integrity despite having reduced bindercontent relative to conventional processes (e.g. less than 3% by weightof the free-standing electrode film in the case of manufacturing an LMOelectrode film for a battery). The electrode film may thereafter belaminated on a current collector (e.g. copper or aluminum) to produce anelectrode in step 140.

FIG. 3 shows another example sub-process of step 110 of FIG. 1 . In theexample sub-process of FIG. 3 , the active material mixture islubricated by the addition of a conductive paste. First, in step 310, anadditive solution may be produced in the same way as in step 210 of FIG.2 , by mixing a polymer additive with a liquid carrier until dissolved.The operational flow of FIG. 3 may then differ from FIG. 2 in theaddition of a step 320 of mixing a conductive material with the additivesolution, resulting in a conductive paste. The conductive material maybe 1-20% by weight of the conductive paste, for example, preferably2-15%, more preferably 5-10%, and may be mixed into the additivesolution using a mill (e.g. in a wet milling process) or a high-shearmixer. Example conductive materials include those identified above inrelation to step 240 of FIG. 2 . The conductive paste may be, forexample, a carbon nanotube (CNT) paste conventionally used to enhanceelectro-conductivity in a wet mixture used in a coating method asexemplified by U.S. Pat. No. 8,540,902. As one example, the conductivepaste may consist of 3.08% (by weight) polyvinylpyrrolidone as thepolymer additive, 91.67% n-methylpyrrolidone as the liquid carrier, and6.25% carbon nanotube as the conductive materials. As explained above,the present disclosure contemplates the use of polymer additivescontained in such a paste to lubricate a predominantly dry or powderyelectrode active material mixture as part of a dry electrodemanufacturing process.

The operational flow of FIG. 3 may continue with a step 330 of mixingthe conductive paste (including the polymer additive, the liquidcarrier, and the conductive material) with an electrode active materialto lubricate the active material surface. The conductive paste may bemixed with the active material using the same methods and amounts asdescribed in relation to mixing the additive solution with the activematerial in step 220 of FIG. 2 . The addition of the conductive paste tothe active material may similarly add only a small amount of liquid,such that the resulting mixture remains powdery.

Once the electrode active material has been lubricated by the conductivepaste, the sub-process of FIG. 3 may continue with a step 340 of addingand mixing in a binder and, in some cases, a step 350 of adding andmixing in a second conductive material other than the conductivematerial included in the conductive paste. Steps 340 and 350 may be thesame as steps 230 and 240 of FIG. 2 . As in the case of the lubricatedmixture produced by the sub-process of FIG. 2 , the lubricated electrodeactive material mixture produced by the sub-process of FIG. 3 may be adry, powdery mixture. In particular, the final mixture to be pressedinto the free-standing electrode film (in step 130 of FIG. 1 ) may havetotal solid contents greater than 95% by weight, with the conductivepaste being less than 5% by weight of the final mixture.

In the example sub-processes of FIGS. 2 and 3 , a conductive material(if any) is added in step 240 or step 350 after the electrode activematerial has been mixed with the additive solution (step 220) orconductive paste (step 330). However, the disclosure is not intended tobe so limited. In some cases, for example, the conductive material maybe added to the active material before the active material is mixed withthe additive solution or conductive paste.

As described above, the free-standing electrode film produced by theprocesses of FIGS. 1-3 may be of high quality, exhibiting goodstructural integrity despite the use of reduced binder as compared withconventional methods. The quality of a film may be quantified using afilm rating system such as the film rating system shown in Table 1,below.

TABLE 1 Score 0 1 2 3 4 5 Wt. Side Tiny Side cracks Side cracks During1st During 1st During 1st 20 Crack pieces. after 1st after 1st press,side press, side press, side Not a press are press are cracks are cracksare cracks are complete larger than larger than less than less than lessthan sheet 7 cm. After 4 cm. After 3 cm. 1 cm. 1 cm. trimming, trimming,After After After final side side cracks trimming, trimming, trimming,cracks are appear on side side no side larger than 2nd and cracks cracksappear 5 cm. continue to appear appear with grow with during 3rd during3rd additional additional or 4th or 4th presses. presses. press butpress but Final side are less are less cracks are than 1 cm. than largerthan 0.5 cm. 3 cm Vertical Tiny Splits Splits During 1st During 1stDuring 1st 25 Crack pieces. during 1st during 2nd press, top press, toppress, top Not a press (either or 3rd press cracks are cracks are cracksare complete from the top (either from less than less than less thansheet. or in the the top or in 3 cm and 2 cm and 1 cm and middle). themiddle). middle no cracks no cracks Crack is Crack is cracks are inmiddle. in middle. larger than larger than less than After After 10 cm.Film 10 cm. Film 5 cm. trimming trimming doesn't doesn't After film, nofilm, no survive survive trimming vertical or additional being beingfilm, no middle vertical pressed 4 pressed 4 vertical cracks crackstimes. times. top cracks appear appear. appear until the until the 4thpress-- 3rd press-- they are they are less than less than 2.5 cm 2.5 cmafter 3rd press and less than 5 cm after 4th press. Middle cracks areless than 9 cm after final press. Flexibility Super Difficult to BreaksWon't Able to be Same as 4 25 brittle. handle but when break loosely buteven Falls can still be moved in a when folded and easier to apart movedwave. Can loosely rolled. handle. when carefully be handled foldedSurvives Can be you try using a file carefully. over or being loosely topick it folder. moved in moved in rolled up up. Very a wave. a wave.several difficult Break Easy to times to when handle. without handle.loosely breaking. rolled. Not too difficult to handle -- file foldereasy to slip under and transport film. Strength Falls Gets holes Failsto be Can be Can be Strong in 25 apart when the picked up picked uppicked up both the easily. micrometer either from the from the verticalDifficult is used or horizontally top top and to when you (by sides) orwithout without horizontal handle. try to pick it vertically breaking.breaking. directions. up. Fails to (by top). Can be Can be Film can bepicked Weak in picked up picked up be picked up either both from thefrom the up from horizontally horizontal sides sides the top (by sides)or (when without without without vertically pulled from breaking.breaking. breaking. (by top). sides) or Strong in Strong in Can be Weakin vertical the the picked up both (when vertical vertical from thehorizontal pulled from direction direction sides (when top and (being(being without pulled from bottom) pulled pulled breaking. sides) anddirections. apart from apart from vertical top to top to (when bottom),bottom), pulled from but weak passable top and in the strength inbottom) horizontal the directions. direction horizontal (being directionpulled (being apart from pulled side to apart from side). side to side).Holes A lot of A lot of A few holes 1 or 2 1 or 2 No holes. 5 (duringholes. holes but with less holes less holes less 1st press) Not 1 still1 sheet. than 2 cm than 1 cm than sheet. diameter. diameter. 0.5 cmdiameter.

Using the example film rating system of Table 1, a film quality scorecan be derived for a film by averaging the scores 1, 2, 3, 4, or 5achieved in each category (“Side Crack,” “Vertical Crack,”“Flexibility,” “Strength, “Holes”) according to the respective weightsof the categories. The higher the film quality score, the greater chancethat the process used to manufacture the film will be scalable to massproduction. In the example film rating system of Table 1, a minimum filmquality score required for successful mass production may be 4.5, forexample.

Experimental results of the above processes are shown in Tables 2-4below. As shown in Table 2, Sample 1 is an LMO electrode made using alubricated active material mixture that was prepared from an additivesolution according to the sub-process of FIG. 2 , and Sample 2 is an LMOelectrode made using a lubricated active material mixture that wasprepared from a conductive paste according to the sub-process of FIG. 3. Comparative Samples 1 and 2 were made without lubrication of theactive material mixture.

TABLE 2 Conductive Paste (including Additive LMO Conductive BinderAdditive Solution) Sample # (g) Carbon (g) (g) Solution (g) (g) Comp. 192 4 4   0 0 Comp. 2 92 5 3   0 0 1 94 4 2.3 2 0 2 94 4 2.1 0 2

Each of the films was evaluated according to the above film ratingsystem of Table 1. The results are shown in Table 3, below.

TABLE 3 Sample Side Vertical Flexi- Weighted Average # Crack Crackbility Strength Holes (Film Quality) Comp. 1 3 3 2 4 1 2.9 Comp. 2 3 2 33 2 2.85 1 4.3 4.4 4.8 4.2 5 4.46 2 4.7 4.7 4.5 4.5 5 4.62

As can be seen, even with less binder being used in Samples 1 and 2, thefilm quality is significantly improved by the use of a lubricatedelectrode active material mixture as described herein.

The bulk resistivity of each of the films was measured, and theelectrodes made using the films were tested to determine their dischargecharacteristics. The results are shown in Table 4, below.

TABLE 4 Bulk 1^(st) Dis. 2^(nd) Dis. Sample Resist. Cap. Effi. Cap. 0.1C 0.33 C 0.5 C 1 C 2 C # (Ω-cm) (mAh/g) (%) (mAh/g) (mAh/g) Comp. 1245.89 101.7 93 102.1 101.8 100.9 99.5 91.5 48.5 Comp. 2 32.38 102.9 94103.3 102.8 102.2 100.5 75.3 35.6 1 20.25 105.9 94 105.7 102.6 105.3104.9 100.5 77.6 2 6.28 104.6 95 105.6 105.5 105 104.1 99 58.3

As can be seen, Samples 1 and 2 exhibited higher discharge capacity andequivalent or higher first cycle efficiency (higher in the case ofSample 2). C rate was also higher for Samples 1 and 2, with nominalcapacity at 0.33C, 1C, and 2C (and 0.1C in the case of Sample 2)increased relative to the comparative samples.

The above description is given by way of example, and not limitation.Given the above disclosure, one skilled in the art could devisevariations that are within the scope and spirit of the inventiondisclosed herein. Further, the various features of the embodimentsdisclosed herein can be used alone, or in varying combinations with eachother and are not intended to be limited to the specific combinationdescribed herein. Thus, the scope of the claims is not to be limited bythe illustrated embodiments.

1. A method of manufacturing a free-standing electrode film, the methodcomprising: preparing a mixture including an electrode active material,a binder, and an additive solution, the additive solution being in anamount less than 5% by weight of the mixture and including a polymeradditive and a liquid carrier, the mixture having total solid contentsgreater than 95% by weight, said preparing comprising mixing theadditive solution with the electrode active material to lubricate theelectrode active material and subsequently adding the binder; subjectingthe mixture to a shear force; and, after the mixture has been subjectedto the shear force, pressing the mixture into a free-standing film. 2.The method of claim 1, further comprising mixing the polymer additivewith the liquid carrier to produce the additive solution.
 3. The methodof claim 1, wherein the polymer additive is 0.5-10% by weight of theadditive solution.
 4. The method of claim 3, wherein the polymeradditive is 1-5% by weight of the additive solution.
 5. The method ofclaim 1, wherein the mixture further includes a conductive material,said preparing comprising mixing the additive solution with theelectrode active material to lubricate the electrode active material andsubsequently adding the binder and the conductive material.
 6. Themethod of claim 1, wherein said pressing includes applying a rollerpress to the mixture.
 7. A method of manufacturing an electrode, themethod comprising: the method of claim 1; and laminating thefree-standing film on a current collector.
 8. A method of manufacturinga free-standing electrode film, the method comprising: preparing amixture including an electrode active material, a binder, and aconductive paste, the conductive paste being in an amount less than 5%by weight of the mixture and including a polymer additive, a liquidcarrier, and a conductive material, the mixture having total solidcontents greater than 95% by weight, said preparing comprising mixingthe conductive paste with the electrode active material to lubricate theelectrode active material and subsequently adding the binder; subjectingthe mixture to a shear force; and, after the mixture has been subjectedto the shear force, pressing the mixture into a free-standing film. 9.The method of claim 8, further comprising mixing the polymer additive,the liquid carrier, and the conductive material to produce theconductive paste.
 10. The method of claim 9, wherein said mixing thepolymer additive, the liquid carrier, and the conductive material toproduce the conductive paste comprises mixing the polymer additive andthe liquid carrier to produce an additive solution and, thereafter,mixing the conductive material into the additive solution.
 11. Themethod of claim 10, wherein the polymer additive is 0.5-10% by weight ofthe additive solution.
 12. The method of claim 11, wherein the polymeradditive is 1-5% by weight of the additive solution.
 13. The method ofclaim 8, wherein the conductive material is 1-20% by weight of theconductive paste.
 14. The method of claim 13, wherein the conductivematerial is 2-15% by weight of the conductive paste.
 15. The method ofclaim 14, wherein the conductive material is 5-10% by weight of theconductive paste.
 16. The method of claim 8, wherein the mixture furtherincludes a second conductive material other than the conductive materialincluded in the conductive paste, said preparing comprising mixing theconductive paste with the electrode active material to lubricate theelectrode active material and subsequently adding the binder and thesecond conductive material.
 17. The method of claim 8, wherein saidpressing includes applying a roller press to the mixture.
 18. A methodof manufacturing an electrode, the method comprising: the method ofclaim 8; and laminating the free-standing film on a current collector.19. A powdery mixture for use in manufacturing a free-standing electrodefilm, the powdery mixture comprising: an electrode active material; abinder; and an additive solution in an amount less than 5% by weight ofthe powdery mixture, the additive solution including a polymer additiveand a liquid carrier, wherein the powdery mixture has total solidcontents greater than 95% by weight.
 20. The powdery mixture of claim19, further comprising a conductive material.
 21. The powdery mixture ofclaim 19, wherein the polymer additive is 0.5-10% by weight of theadditive solution.